Perioperative Systemic Chemotherapy, Cytoreductive Surgery, and Hyperthermic Intraperitoneal Chemotherapy in Patients With Colorectal Peritoneal Metastasis: Results of the Prospective Multicenter Phase 2 COMBATAC Trial

Abstract Background Cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) as parts of an interdisciplinary treatment concept including systemic chemotherapy can improve survival of selected patients with peritoneal metastatic colorectal cancer (pmCRC). Nevertheless, the sequence of the therapeutic options is still a matter of debate. Thus, the COMBATAC (COMBined Anticancer Treatment of Advanced Colorectal cancer) trial was conducted to evaluate a combined treatment regimen consisting of preoperative systemic polychemotherapy + cetuximab followed by CRS + HIPEC and postoperative systemic polychemotherapy + cetuximab. Patients and Methods The COMBATAC trial is a prospective, multicenter, open-label, single-arm, single-stage phase 2 trial. Twenty-six patients with synchronous or metachronous colorectal or appendiceal peritoneal carcinomatosis were included. Enrollment was terminated prematurely by the sponsor because of slow recruitment. Progression-free survival as primary end point and overall survival were estimated by the Kaplan-Meier method. Also evaluated were morbidity according to Common Terminology Criteria for Adverse Events v4.0 and feasibility of the combined treatment concept. Results Median progression-free survival for the intention-to-treat population (n = 25) was 14.9 months. Median overall survival was not reached during the study duration. Ninety-two adverse events were documented in 16 patients, including 14 serious adverse events in 9 patients. The overall morbidity rate was 64%, and the grade 3/4 morbidity rate was 44%. Of all grade 3/4 morbidity events, 36.4% were related to systemic chemotherapy and 22.7% to surgery, whereas 40.9% were not directly related. There was no treatment-related mortality. Conclusion The results of the COMBATAC trial show that the multimodal treatment concept consisting of perioperative systemic chemotherapy and CRS + HIPEC is safe and feasible. Progression-free survival in selected patients with colorectal or appendiceal peritoneal metastasis might be improved.